BOSTON (AP) — Eleanor McCullen clutches a baby’s hat as she patrols a semicircle painted on the sidewalk outside a health clinic on a frigid December morning.

The painted line marks 35 feet (10 meters) from the clinic’s entrance, and that’s where the 77-year-old McCullen and all other abortion protesters and supporters must stay. Now the Massachusetts law that created the buffer is being challenged at the U.S. Supreme Court as an unconstitutional infringement on free speech. Arguments are set for Wednesday.

Outside the line, McCullen and others are free to approach anyone with any message they wish. They risk arrest if they get closer to the door.

McCullen has become the new face of a decades-old fight between abortion opponents asserting their right to try to change the minds of women seeking abortions and abortion providers claiming that patients should be able to enter clinics without being harassed.

McCullen and other abortion opponents sued over the limits on their activities at Planned Parenthood health centers. Planned Parenthood provides health exams for women, cancer screenings, tests for sexually transmitted diseases, birth control and abortions.

Before the zone went into effect in 2007, protesters could stand next to the entrance and force patients to squeeze by, said Marty Walz, president and CEO of Planned Parenthood League of Massachusetts.

Other than Walz, people at the clinic refused to have their faces photographed because they fear anti-abortion activists would post the pictures online.

They worry about safety. In 1994, a gunman killed two receptionists and wounded five employees and volunteers at a Planned Parenthood facility and another abortion clinic in nearby Brookline. The most recent killing was in 2009, when Dr. George Tiller, who performed abortions, was shot in a church in Kansas.

Mark Rienzi, the Catholic University law professor who represents the protesters, said there has not been a documented case of violence at a Massachusetts clinic since the 1994 killings.

“The idea that someone like that will be deterred by a painted line on the ground is nonsensical,” he said. “In the meantime, you shouldn’t be able to use that to stop women from being offered these other options.”

The protesters said the law limits their ability to be on a public sidewalk with a message that they have a right to express.

“Unless I’m quick enough to make it around the perimeter of the buffer zone, I don’t have the opportunity to talk to people face to face or put a leaflet in their hand,” said Bill Cotter of the anti-abortion group Operation Rescue.

One cold morning, McCullen and a few other protesters were handing out roses.

“Every child deserves a birthday. Save a child today,” one man said whenever people entered the clinic.